Connecting the refrigerator start relay: diagram, tools and step-by-step installation

When the refrigerator suddenly stops freezing, but the light inside is on and the compressor does not make the usual hum, the culprit is often it turns out starting relay. This small but critical element is responsible for starting the motor-compressor, and its malfunction paralyzes the operation of the entire system. You can connect the relay yourself even without experience in repairing equipment - the main thing is to understand connection diagram, prepare tools and follow a clear algorithm.

In this article we will look at how to properly connect the starting relay to refrigerators of different brands (Atlant, Indesit, Samsung etc.), which types of relays exist (induction, posistor, electronic), and why it is important to consider polarity during installation. You will also learn how to check the functionality of the relay with a multimeter and avoid common mistakes that lead to repeated breakdowns.

What is a starting relay and why is it needed

A starting relay is electromechanical or electronic devicewhich briefly connects starting winding the compressor at the time of its start. Without a relay, the motor simply will not be able to start rotating, since the required starting current is 3-5 times higher than the rated one.

In modern refrigerators three types of relays are used:

• 🔄 Induction — classic relays with a coil and a core (installed on old models ZIL, Minsk).
• 🔥 Posistor —with a thermistor that heats up and opens the circuit (popular in LG, Samsung).
• 📱 Electronic - completely contactless, with protection against overheating (used in inverter compressors Panasonic, Hitachi).

The main task of the relay is breaking the starting circuit 0.5-2 seconds after starting the compressorto avoid burning the windings. If the relay sticks or does not work, the motor either does not start or operates with overload, which leads to turn-to-turn short circuit.

Tools and materials for connection

Before starting installation, prepare everything you need. Without the right tools, you risk damaging compressor terminals or incorrectly fastening the contacts, which will lead to a short circuit.

You will need:

• 🔧 Screwdrivers - Phillips and flat (for dismantling the relay cover and fastening the compressor).
• 📏 Multimeter - to check the winding resistance and circuit integrity.
• ⚡ Insulating tape or heat shrink tube — for insulating connections.
• 🔌 Pliers —for crimping terminals (if detachable connectors are used).
• 🧲 Magnet —to avoid losing small screws when disassembly.

Also prepare one a new relaythat is compatible with your refrigerator model. Check its brand on the sticker on the old relay or in the documentation for the compressor. For example, Embraco EG is suitable. relay Danfoss 103N0210, and for Secop (DWM) — QP2-4.5.

Connection diagram for the starting relay to compressor

The standard relay connection diagram is the same for most refrigerators, but may differ depending on type. compressor (single-phase, three-phase) and number of contacts on the relay. Let's consider a universal option for household models.

The refrigerator compressor has three outputs:

• C (Common) — common contact (connected to the relay and thermostat).
• S (Start) — starting winding (connected only via a relay).
• R (Run) — working winding (goes directly to the network).

The relay is connected as follows:

1. Contact C compressor → terminal M (or COM) on the relay.
2. Contact S compressor → terminal S on the relay.
3. Terminal L (or Line) on the relay → phase wire of the network (220V).
4. Terminal N (if any) → neutral wire of the network.

⚠️ Attention: If you mix up S and R, the compressor will not start or will overheat. On some relays, the terminals are marked differently (for example, 1, 2, 3) - check the documentation!

How to identify the contacts if the markings are erased?

If there are no symbols on the compressor, use a multimeter: the resistance between C and S should be 2-3 times greater than between C and RFor example, if C-R = 10 Ohm, then C-S ≈ 20–30 Ohm.

Step-by-step instructions for connecting a relay

Now let's move on to practice. Follow this algorithm to avoid mistakes:

1. Disconnect the refrigerator from the mains and turn it back to access the compressor.
2. Remove the protective casing compressor (usually secured with 2-4 screws).
3. Disconnect the old one relay:
   • Unscrew the screws securing the relay to the compressor.
   • Carefully remove the terminals from the contacts (memorize or photograph their location!).
4. Connect the new relay:
   • Connect the terminals according to the diagram (see previous section).
   • Fast the relay on the compressor (the screws must be tightened tightly, but without pinching).

Check the reliability of the contacts - pull the wires, they should not become disconnected.

Put the casing in place and turn on the refrigerator at network.

⚠️ Attention: If after connection the compressor hums, but does not start, immediately turn off the power! This is a sign of turn-to-turn short circuit or incorrect connection of the starter! windings.

Checking the functionality of the relay with a multimeter

Before installing a new relay, make sure that the old one is really faulty. To do this, do the following. measurements:

1. Relay coil test:
   • Switch the multimeter to mode 200 Ω.
   • Connect the probes to the terminals S and M (or COM).
   • Resistance should be within 10–50 Ohm (for inductive relays). If ∞ —break, if 0 —short circuit.
2. Checking contacts:
   • In the dialing mode (─| |─), check the circuit between L and M with the relay closed (for this you can manually press the core).
   • If the circuit does not ring - the contacts are burnt.

For posistor relays (with a tablet) check the resistance of the posistor:

• In a cold state: ~20–50 Ohm.
• After heating (for example, with a hairdryer): the resistance should increase to kOhm.

If at least one of the tests fails, the relay must be replaced. Posistor relays cannot be repaired: their tablet degrades over time and requires complete replacement node.

Typical errors and how to avoid them

Even experienced technicians sometimes make mistakes when connecting a relay. Here are the most common ones and ways to prevent them:

• ⚡ The terminals are mixed up S i R → the compressor does not start or operates with overheating. Solution: Always check the diagram and markings on the compressor.
• 🔌 Weak contact of the terminals → sparking, heating, burning wires. Solution: Crimp the terminals with pliers and check the reliability of fastening.
• 🔥 Using a relay with inappropriate parameters → protection operation or startup failure. Solution: Check the compatibility of the relay with the compressor model (for example, Danfoss 103N suitable for motors with power up to 1/4 hp).
• 🛠️ Forgot to insulate exposed wires → risk of short circuit. Solution: Use heat-shrink tubing or electrical tape.

Another common problem is oxidation of contacts on old compressors. If the terminals are covered with a green coating, clean them sandpaper (P600–P800or with a special liquid for contacts (Contact Cleaner).

Features of connecting the relay in refrigerators of different brands

Although the principle of operation of the relay is the same, refrigerator manufacturers sometimes make their own adjustments to the connection diagrams. Let's consider the nuances for popular brands:

⚠️ Attention: In refrigerators Samsung with a system Digital Inverter specialized relays are used that are not interchangeable with conventional ones. Attempt to install a generic relay may damage the compressor controller.

How to connect the relay in refrigerators with two compressors?

In two-compressor models (for example, Atlant MXM-2835) each relay is connected to its motor independently. The main thing is not to confuse the power wires and signal cables from the thermostat.

FAQ: Frequently asked questions about connecting the relay

Is it possible to connect a relay from another refrigerator?

Theoretically, it is possible, but only if they match:

• Relay type (inductive/posistor/electronic).
• Rated current (indicated on the relay body).
• Resistance of the compressor starting winding.

For example, a relay from Atlant is suitable for Turkiesif they have the same compressors DXM-5But a relay from LG not suitable for Indesit due to different connection diagrams.

Why does a new relay burn out immediately after installation?

The reasons may be the following:

• Short circuit in the compressor windings (check the resistance with a multimeter).
• Incorrect connection polarity (relevant for electronic relays).
• Voltage surges in the network (use stabilizer).
• Overheating of the compressor due to a faulty capacitor.

If the relay burns out again, diagnose the compressor and the electrical circuit of the refrigerator.

Do I need to solder the wires when connecting the relay?

No, solder not necessary. In most cases, crimp connectors are used. Soldered connections may crack due to vibration of the compressor. If the terminals are damaged, replace them with new ones (for example, plug-in terminals detachable terminals or crimp connectors. Soldered joints can crack due to compressor vibration. If the terminals are damaged, replace them with new ones (for example, Faston 6.3 mm). data-i="283">How to check a relay without a multimeter?).

How to test a relay without a multimeter?

You can use a test lamp (220V, 40W):

1. Connect the lamp in series with the relay in the circuit L–M.
2. If, when power is applied, the lamp lights up and goes out after 1-2 seconds - the relay is working properly.
3. If the lamp does not light up or is constantly on, the relay is faulty.

⚠️ Be careful: working with a 220V network requires compliance with safety precautions!

What to do if, after replacing the relay, the compressor works, but the refrigerator does not freeze?

The problem is not in the relay. Possible reasons:

• Freon leak (refill required).
• Malfunction of the thermostat or temperature sensor.
• Fan jammed (in models with No Frost).
• Clogged capillary tube.

Diagnose the system in order: first check the thermostat, then the pressure in the circuit.